Hong-Kong
based YS-Audio was founded in 1988 by designer Chui Yat Sang and has been
focused on quality valve products since then. Their gear now bears the logo "Audio
Experience" and is available for sale online and certainly on eBay. Note
that my review sample was delivered by The Pacific Valve and Electric Company
(PV), which in their own words "was created to fill the need of high end audio,
particularly tube equipment, at a reasonable price point." Audio gear is
imported primarily from China.

I was
told that PV's relationship with all their vendors is that of an
importer/retailer, rather than importer/distributor, since product is not
offered for re-sale in other outlets. PV also does not demand exclusivity,
the benefit being that they can "cherry pick" products to offer on
their website - as opposed to carrying the entire manufacturer's line. Following
this business model allows PV "to reach out to many manufacturers globally, who
prefer this model, and carry equipment that we think is: 1) unique in design, 2)
offers the best value 3) gives us a competitive advantage from a
price/performance level." This, I'm told, is the "Long Tail" approach to
marketing and retailing – the niche strategy of selling a large number of
unique items in relatively small quantities. It does strike me as a splendid
model for satisfying audiophiles' needs. It is also important to point out that
the selection process involves a listening panel of staff and friends, and once
an item passes, it is evaluated by the PV techs for construction quality and
tolerances. Repairs are performed in-house. Each product sold is branded with a
PV serial number to ensure warranty repair service. However, PV does not repair
similar product purchased by consumers directly from overseas or on eBay.

Technical DetailsThere was
a time some thirty years ago when a preamplifier was purchased primarily on the
basis of its phono stage quality. The line section was merely an adjunct for
providing additional gain for the phono input and for servicing secondary
line-level sources such as tuners and tape decks. Today the line stage or line
preamp has become objectified as a darling of high-end audio. Prices in excess
of $10,000 at the retail level are commonplace. The funny thing is that if you're
strictly into CD/SACD playback then in most applications you actually don't even
need any gain. Many line stages insert 20 dB of gain into the chain, which for a
nominal CD input level, has to be attenuated by the volume control. That's plain
silly. A buffer stage with a volume control would fit the needs of most digital
front ends very nicely indeed. And I'm specifically thinking here of Nelson Pass's
First Watt B1 buffer stage. I have made the suggestion some time ago that a line
preamplifier should dedicate at least one input as buffer stage, giving the user
more flexibility in configuring his or her system. As far as I can tell, no
manufacturers have taken up such an approach.

So
if gobs of gain is not a priority for a line preamp, then there is little reason
to engineer the circuit with more than a single gain stage. That's exactly the
approach taken by YS Audio: keep the circuit as simple as it needs to be. A
single SRPP gain stage is followed by a buffer stage. Unusually for this price
point, the circuitry offers balanced amplification. Two 12AT7 dual triodes are
used per channel for amplification of both the hot and cold signals (pins 2 and
3 on the XLR connector). A single 5687 computer-grade tube is used per channel
as a buffer stage. A clever resistive phase inverter network is used to balance
the single-ended input. In case you're wondering why the unit is not phase
inverting with only a single voltage gain stage, polarity is reversed internally
at the outputs to maintain normal phase.

The
signal passes through two potentiometers before reaching the grids of the first
stage. The first pot allows for setting channel balance and for overall gain
trim. The second pot acts as a stereo volume control. The volume control is a
motorized Alps pot with a remote that also controls input source selection.
There are four sets of balanced and unbalanced inputs, two sets of balanced and
un balanced outputs, a record out, and a home theater bypass loop. A 60- second
soft-start circuit ramps up plate voltages in a controlled manner. One minor
grip. The Power On LED is so bright as to be a distraction in a dimly lit room.
My solution was to tape it over. The power supply uses a compact R-core power
transformer, is solid-state rectified, and plate voltages are regulated.

Note that the unit under review is the Special Edition (SE) version of
the A2. This SE version is upgraded with premium Cardas CTFA RCA jacks, Neutrik
XLR connectors, and Sonicap coupling capacitors. All in all, a worthwhile
upgrade, considering that connectors can have a significant sonic impact on
overall sound quality.

Sonic ImpressionsWhat do
you do when you have a balanced power amplifier (Electrocompaniet AW180) in
house for review and none of your preamps offer balanced operation? Well, the
first option is to use an XLR to RCA adapter. I did that, and by the way, I can
safely recommend the Cardas adapter as far superior sonically to any of the mass
market versions. I've been a single-ended guy for too long to accept balanced
operation as necessarily superior for home audio applications, but in terms of
the evaluation it was essential to mate the AW180 with a balanced preamp. Option
two, therefore, was to go shopping for a balanced preamp, and that's how the
A2-SE materialized in the reference system and was put to good use.

Integrating
a preamp successfully into any system is very much dependent on compatibility
with the associated system components. With the DALI Helicon 400 Mk.II
loudspeakers, the A2-SE made a fabulous first impression, especially when
operated in balanced mode. And in hindsight, it is clear that there was
undeniable synergy in the air. Its sonic strengths were readily apparent:
transparent soundstage, tight, palpable image outlines, and rhythmic delivery
highly resolving of timing nuances. Speed of attack combined and clarity of
transient decay were exceptional for a tube preamp. The midrange was slightly
sweet, imbued with a touch of natural warmth solid-state amplification
desperately needs a dose of. Brushed cymbals sounded just right with plenty of
high-frequency air. Bass lines were not only tight, but it was apparent that the
A2-SE could elicit terrific bass punch from the AW180.

The
A2-SE spent a fair amount of time going heads up against the more expensive Mystère
CA21 Line Preamplifier ($2195). The latter features a tube-rectified power
supply and 6SN7 based gain and buffer stages. It's single-ended, but
conceptually similar to the layout of the A2-SE. I have for some time now
substituted NOS 7N7 and 7AF7 Loktals for new production Russian and Chinese 6SN7
which frankly stinks. So outfitted, the Mystère is capable of generating a big
tone lower midrange which no 9-pin miniature seems able to match. The A2
certainly did not fatten up the AW180's lower mids and in general lacked the
Mystère's rich harmonic textural density. Aside from the choice of triodes, I
suspect that some of the sonic difference is due to solid-state versus tube
rectification. A least in my experience, tube rectified preamps have been able
to portray harmonic textures with a density approaching that of the real thing.
Harmonic colors also appear more saturated through an all-tube unit. I would be
most interested to audition a tube rectified version of the A2-SE.

The
situation was more complex with the MartinLogan Summit X hybrid electrostatics.
The Summit has few peers when it comes to low-level detail retrieval, transient
speed, and purity of tone. Yet, it can overload a room with an over abundance of
treble energy. I began to complain of a hyper-detailed, bright and texturally
thin presentation and I presumed that the stock JAN Philips 12AT7 tube
complement was partly to blame. Thus I embarked on a couple of tube rolling
experiments designed to obtain richer textures and a slightly darker
presentation. The winner turned out to be a NOS quad of GE 12AT7WA vintage 1954,
black plates with triple mica spacers. Darker, yes, richer, yes, but at the end
of the day, I had to accept the fact that the A2-SE was simply not the best
match for the Summit, being too lively and forward through the treble range.
Believe me, this is the wrong sonic personality for the Summit. With my
Basszilla Platinum Edition Mk.2 DIY speaker, the A2-SE exceeded the Mystère
CA-21's performance in terms of detail resolution and timbre accuracy. Yet, it
lacked the CA21's big tone, and even when outfitted with upgraded 12AT7s it
projected a brighter and more forward balance.

ConclusionIt
should be clear by now that the Audio Experience A2-SE requires careful system
matching for optimum performance. It can lock-in on a Goldilocks
-- just right tonal balance -- or at the other extreme project too
lively a balance that is bound to interfere with long-term listening enjoyment.
Its sound can best be summarized as fast, transparent and adept at reproducing
timing nuances. It avoids typical tube euphonics, yet captures sufficient tube
magic when it comes to image palpability and textural sweetness. The flexibility
to accommodate both single-ended and balanced systems is quite a bonus. The
A2-SE is in my estimation quite a remarkable performer at its price point and
deserving of a serious audition.